This invention relates to cartoning apparatus and more particularly to apparatus for receiving and feeding carton blanks in a downstream direction toward a cartoner which erects, fills and seals the cartons.
In handling cartons, it is known to provide a carton feeder for receiving flattened carton blanks in bulk and delivering flat blanks individually to a conveyor or other cartoning apparatus. Such feeders typically include a blank magazine which is oriented either vertically, horizontally or inclined. Flattened carton blanks are delivered in bulk to the magazine, forming a xe2x80x9cstackxe2x80x9d of blanks. Such stacks generally have a bottom end, from which cartons are picked off, one after the other and a top end against which more flattened blanks are loaded as desired.
In the vertical and inclined magazines, the bottom end of the carton stack is generally the lower end while the upper end of the stack is the top end. In the horizontal magazine, the downstream end of the stack in the machine direction is usually deemed the bottom end while the upstream end of the stack is the top end. In such horizontal magazines, it is not unusual for the blanks to have their respective upper edges tilted toward a downstream direction, i.e. toward the stack bottom. Thus the downstream or bottom end blanks bear the stack pressure from the top end or upstream blanks leaning against them. When a carton is picked off the downstream or bottom end, it must be handled in a way to differentiate it or separate it from the stack. This is sometimes accomplished by pick-off mechanisms comprising escapements, or the like, with fingers holding the stack while a suction cup or a gripper pulls off the bottom-most blank.
Of course, the steeper or more vertically oriented the stack, the higher the pressure exerted by the stacked blanks on the bottom-most blanks requiring substantial control and xe2x80x9chold-backxe2x80x9d mechanisms, for all but the blank being released. Depending on the flexibility and size of the blanks, these devices either unduly interfere with free release of the bottom-most blank, or permit undesirable release of following blanks. Large flimsy blanks, for example, could fall through short hold-back fingers.
This invention comprises an improved feeder primarily configured in a horizontal or other slightly inclined magazine, where nevertheless the stack of cartons usually leans with upper edges forwardly so that the stack weight leans on or is coincident on the lower cartons of the stack""s forward or bottom end. This pressure ordinarily complicates the removal of a bottom-most carton for feeding one after the other.
The invention contemplates the handling of the stack to redefine the stack dynamics and pressures exerted by the stack on the cartons therein. In other words, the invention contemplates reorientation or reversal of the stack or its dynamic configuration so that stack pressures are not exerted on the so-called bottom-most carton blanks ready to be fed. This enables use of a much simpler and less costly pick-off mechanism without concern over multiple carton releases due to stack or feed pressures or use of detailed pick-off devices or escapements. At the same time the stack dynamic is retained at the stack top or supply end so further blanks are easily loaded.
To these ends, the invention contemplates a generally horizontal or inclined magazine holding carton blanks with upper edges leaning forwardly in a machine or a feed direction where they pressure downstream carton blanks. Nevertheless, proximate the position where carton blanks are picked off, the dynamic nature of the stack is changed. Specifically, the tops of the cartons are stabilized or confined in a choke or standing wave acting like a choke, while the bottom edges of the cartons are driven through a greater linear distance than the carton""s top edges. This creates a form of standing wave in the carton blank stack producing several cartons at the forwardmost or bottom end of the stack now inclined with their upper edges rearwardly.
In other words, the inclinations and thus the dynamics of the stack are reversed, thus relieving the leading or forwardmost carton from all upstream generated pressure forces exerted by leaning cartons.
Since the carton top edges of a few cartons now at the stack""s downstream end are so inclined rearwardly, there is no undesirable stack pressure on the downstream-most carton ready for pick off. Pressures exerted by it on the stack are no more than pressures exerted by the stack rearwardly toward the last-loaded blank at the so-called stack top.
As a result, if the entire load of the cartons in the feeder is considered from the downstream-most carton ready for pick-off rearwardly through the last carton in the advancing stack at the stack top, then the stack has one top end at its upstream position and another downstream-most end where the cartons there are not affected by pressures of cartons stacked upstream, and thus also comprises a xe2x80x9ctopxe2x80x9d end. Thus the entire load or stack of cartons in the feeder has two top ends from the standpoint of carton condition as a function of stack pressure, both of which facilitate a function such as top loading (cartons inclined forwardly) or top feeding (cartons inclined rearwardly).
Accordingly, carton blanks can be fed to the stack top in the magazine and individual cartons can be removed from the other end of that stack, which by virtue of the interim dynamic stack reversal also functions as if it were at the xe2x80x9ctopxe2x80x9d of the stack (i.e. bearing no pressure from the weight of cartons above or upstream of it).
In this manner, simple suction cup/segmented wheel pick-off or other mechanisms can be used without undue concerns of feed or stack pressures ramming proximate cartons out the discharge to the pick-off mechanism and jamming it.
In a preferred embodiment of the invention, a carton magazine comprises a first set of two parallel running carton supporting and conveying chains. Cartons are deposited perpendicularly across these with lower edges on the chain and upper edges inclined forwardly of the lower edges. Each carton bears the weight of upstream cartons leading on or toward it.
At a xe2x80x9cstack reversalxe2x80x9d station, the upper edges of the cartons are restrained at a choke point, preferably by a forward stabilizer, and the lower edges driven onto a second set of two further parallel running chains, preferably slightly inclined upward then declined downwardly. This second set of chains runs faster than the first set so the bottom of the cartons are carried a linear distance longer than the tops, thus reversing their inclination so the top carton blank edges trail the lower edges (i.e. blanks now lean rearwardly).
Thereafter, a third set of parallel running chains conveys the cartons forwardly toward a pick-off point, the lead carton being free of the weight or pressure of succeeding cartons.
Each set of conveyor chains is driven by an independent motor or servo, each of which is controlled at least in part by a respective sensor. A first sensor controlling the first motor for the first set of magazine chains is disposed at the upper edges of the cartons just prior the choke or xe2x80x9cwavexe2x80x9d area. If the stack is too inclined, so the blank tops do not trip the sensor, the first motor is energized to feed more blanks.
A second sensor is located to sense carton blank top edges downstream of the choke. If the top edges decline too low, the second sensor trips to energize the second motor to drive the second set of chains to drive more cartons through the reversal station.
A third sensor is oriented at the bottom of the cartons at the discharge or pick-off station. If insufficient cartons exist to operatively engage this sensor, it energizes the third motor to drive the third set of chains to supply more cartons to the pick-off station.
Of course, the servos could be controlled by proportioning sensors to operate at varying speeds within preset parameters, but the on/off sensor operation described above is useful. Also, algorythms could be provided to control motor speeds or operation to produce a desired effect.
Moreover, the xe2x80x9cchokexe2x80x9d of the carton blanks in a reversal station can be by mechanism obstruction such as a stabilizer as shown, or, alternately, simply comprised of what appears to be an unconfined standing wave corresponding somewhat to a position over the inclined, declined second set of chains.
Thus, the benefits of loading a carton magazine at the top end are maintained while feeding off the xe2x80x9ctopxe2x80x9d of the stack, from a functional standpoint, is provided to make the feed and carton pick-off more reliable by eliminating carton weight and pressure at the pick-off station. Thus, the top-load, top-feed feeder provides a useful, unique and improved feeder which can also accommodate both CMH and CMC cartoner operation.
Also, such a feeder more readily accommodates larger, flimsier carton blanks which may otherwise fall through an escapement or edge hold-back mechanism at the discharge end.
It is also contemplated that apart from blanks, the invention could easily be used to feed other diverse materials such as sheets, CDs, discs, plates, planar or nestible objects or the like.